Walk into any bank, they will issue against FD/liquid security immediately. Unsecured is like a loan so it will take time accordingly. BUT check with wherever you are submitting Bank Guarantee like if they want performance guarantee or financial guarantee (common ones), are there any specific clauses to be included in guarantee, government department generally accept guarantees from PSU banks, some departments may want to accept guarantee only from there nearest bank. Generally guarantees are directly sent by banks to beneficiary but some officers will demand you deposit it in person with some sweets* for them. If you need to furnish guarantee to foreign entity then you will require counter-guarantee which your bank will arrange but it takes time and money. You will have to pay service charge+issuance charges+stamp duty+postage. In case of unsecured interest will also be payable